Kinetics and Mechanism of the Reaction of Triphenylphosphine with Methyl Vinyl Ketone

Russian Journal of General Chemistry - Kinetics of the reaction of triphenylphosphine with methyl vinyl ketone has been studied using the stopped flow technique. The experimental data have...     

Observation of dielectronic satellites in the K-spectrum of argon ions in plasma produced by femtosecond laser pulses

The satellite structure of 1s2p ^1,3 P ₁-1s ²¹ S ₀ lines of the He-like argon ion in plasma produced by a 45-fs laser pulse in a gas-jet cluster target is measured with a high spectral resolution. Radiation transitions 2p → 1s from autoionizing states (AISs) are detected for ions ranging from Li-like to F-like. The spectrum observed is theoretically simulated with the use of the spectroscopic data for the AISs of multicharged ions obtained within the multiconfiguration relativistic Hartree-Fock method. Good agreement with experimental data is obtained when the main population channels of these states are taken into account for typical values of cluster-target plasma parameters.     

Effects of localization of the areas of sound scattering by surface wind waves

Experimental studies of the scattering of a monochromatic sound signal by a rough sea surface are carried out. The signal is produced by a point source in a shallow-water basin. The measurements are performed with the use of horizontal and vertical linear receiving arrays. The experimental data are compared with the estimates obtained on the basis of the model developed by the authors for resonant sound scattering by surface roughness. A satisfactory agreement between the experiments and the calculations is achieved. It is shown that the scattered signal is formed within small surface areas, whose sizes have the same order of magnitude as the first Fresnel zone with respect to the source and the receiving system.     

Theoretical study of single-electron capture in He2+ —H− collision

We present a detailed theoretical treatment of single-electron transfer between He²⁺ and H^?. The total cross section is calculated using stationary molecular states which are appropriate in the energy range covered by the experiments (between 0.5 and 2250 eV in the centre of mass frame). We use an expansion on a two-electron basis built with one-electron diatomic molecule (OEDM) orbitals and including the common translation factor of Errea et al. All coupling terms are calculated explicitly. Because of the small binding energy of H^? compared to that of the ground state of He⁺, capture occurs into highly excited states of He⁺. Results obtained with a straight-line quasiclassical calculation are in good agreement with the experimental data. At low energy, He⁺ (n=5) +H(1s) is the dominant capture channel; at higher energy, the He⁺ (n=4) + H(1s) channel becomes important. The rise in the cross section below 6 eV can be attributed to the Coulomb attraction in the incoming channel. To account for this effect, a fully quantal calculation has been performed. The agreement with the low-energy measurements is then excellent.     

An electronic aid for line selection for scanning inductively coupled plasma atomic emission spectrometers

This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta Part B (SAB). Accompanying this hard copy text is a disk containing the program, source flies, data files and a brief manual along with a few programming notes. The main article discusses the purpose of this work, and the Appendix provides brief instruction on the use of the program, manipulation of the data, and source code. An automatic file selection system for the control of a rapid scanning spectrometer performing atomic emission spectrometry has been developed using the PROLOG language. The system can be “taught” the elemental composition of a given sample type. It uses this information (when available) to generate a linear search strategy which minimizes the number of lines that need to be measured. The rules used by the system can be observed during system operation to allow a trace of the logic. Reading of the initial data base takes no more than 6 s and then decisions are made in less than 1 s per line.     

A versatile low-cost laboratory computer network

An inexpensive but powerful computer network particularly suited to the research laboratory is discussed. The primary advantages of the system are low cost, flexibility, freedom of choice of manufacturer, and convenience of upgrading. The principal limitations are speed of data transfer and the requirement for a certain level of skill during setting up. The system operates with both the CP/M and MP/M operating systems, but the principles of operation are generally applicable.     

Electron capture in high-energy ion-atom collisions

We discuss the non-relativistic theory of electron capture from atoms (or ions) by ions when the relative velocity of the collision is greater than the orbital velocity of the captured electron. We emphasize the specific difficulties due to the two-body Coulomb potentials occurring in this process We show how the simplifications introduced by the small value of the electron to proton mass ratio can be used to provide a valuable tool to evaluate the adequacy of the existing theories. Extensive comparisons between theory and experiment are carried out and a number of new theoretical results are presented.